Fix golangci-lint errors and enforce lint in CI

[aravindtga]

Description

• What changed: Fixed all golangci-lint errors (errcheck, gosec, staticcheck) across go/fn and added || exit 1 to the lint-modules Makefile target so lint failures actually break CI.
• Why it's needed: The lint target was silently swallowing failures - golangci-lint could fail without affecting the CI result. Additionally, several unchecked return values and a path traversal warning needed addressing.
• How it works:
  • internal/docs/render.go: Explicitly discard fmt.Fprint/fmt.Fprintf return values with _, _ =
  • run.go: Same for fmt.Fprint calls; use filepath.FromSlash + //nolint:gosec for CLI-arg file reads
  • Test files: Use _ = for Close() calls, fmt.Fprintf instead of WriteString(fmt.Sprintf(...)), wrap os.RemoveAll in closure
  • go/Makefile: Add || exit 1 to lint-modules loop so lint failures propagate

Related Issue(s)

• N/A

Type of Change

• Bug fix
• Enhancement

Checklist

• Code follows project style guidelines
• Self-reviewed changes
• Tests added/updated
• Documentation added/updated
• All tests and gating checks pass

AI Disclosure

• I have used AI in the creation of this PR.

If so, please describe how:
- Kiro to identify and fix all golangci-lint errors and the CI gating issue.

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

This PR primarily addresses lint-related error handling for I/O operations and introduces path sanitization when reading resources from files.

Changes:

• Explicitly ignore or capture return values from Close()/Fprint()/Fprintf() to satisfy error-checking linters.
• Use fmt.Fprintf in the property test generator to avoid fmt.Sprintf allocation.
• Apply filepath.Clean before os.ReadFile in file-mode execution.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 14 comments.

Show a summary per file

File	Description
go/fn/run_flags_test.go	Updates test helpers to explicitly ignore Close() errors.
go/fn/run_filemode_property_test.go	Uses fmt.Fprintf into a buffer and ignores RemoveAll error in defer.
go/fn/run.go	Cleans file paths before reading; explicitly discards fmt.Fprint return values.
go/fn/internal/docs/render.go	Explicitly discards fmt.Fprint/Fprintf return values during help rendering.
go/Makefile	Ensures golangci-lint failures stop the lint-modules loop.

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[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 4 comments.